Capillary inlet



May 17, 1960 J. B. THOMAS 2,936,599

CAPILLARY INLEIT Original Filed Oct. 15, 1954 INVENTOR.

JESSE B. THOMAS ATTORNEY CAPILLARY INLET Jesse B. Thomas, Louisville, Ky., asslgnor to Reynolds Metals Company, Richmond, Va., a corporation of a Delaware Original application October 15, 1954, Serial No. 462,471, now Patent No. 2,821,845, dated February 4, 1958. Divided and this application July 10, 1957, Serial No. 671,074

6 Claims. 01. 62-527) It is desirable to have the incoming liquid refrigerant of a refrigerator evaporator, precooled by heat exchange contact with the outgoing efiluent liquid or gaseous refrigerant. Accordingly, where the incoming liquid refrigerant is supplied through a capillary tube, that tube is placed in heat exchange relationship with the outgoing gas conduit.

Also, in making aluminum evaporators of the pressure welded passageway panel type, it is quite difiicult to form a refrigerant-inlet passage accurately to the small size required for it to function as a capillary tube. Furthermore, Where the evaporator is made of aluminum, it is diflicult to bond a separate capillary tube to the aluminum so that the difficulties of manufacture are increased. The present invention is directed to the problem of providing pressure welded passageway panels with capillary inlet tubes.

The present application is a division of my co-pending application 462,471, filed October 15, 1954 which issued Feb. 4, 1958 as Patent No. 2,821,845. The latter relates to evaporators of the pressure welded passageway panel type and claims a novel capillary tube arrangement wherein the capillary tube extends through the outgoing gas conduit so that its outer wall is in direct heat exchange relationship with said gas. The present application claims another arrangement wherein the capillary tube extends through another conduit, which is laterally adjacent to and in heat exchange relationship with the outgoing gas conduit.

An object of the present invention is to provide a pressure welded refrigerator evaporator panel having a capillary tube which is mounted substantially rigidly on the panel in heat exchange and non-contacting relationship with the refrigerant in the panel evaporator chamber.

Another object of the present invention is to provide a pressure welded refrigeration evaporator panel having a capillary tube extending through a sheathing conduit in heat exchange relationship with the panel evaporator chamber with the sheathing conduit being separate from the evaporator chamber.

Another object of the present invention is to provide a pressure welded refrigeration evaporator panel having a capillary tube sheathing conduit which is separate from and in heat exchange relationship with the panel evaporator chamber.

According to the present invention I provide an improved evaporator panel structure by which the capillary tube is maintained throughout its circumference in heat exchange relation but in non-contacting relation to the efiluent vapors or liquid in the evaporator chamber of the panel. That is, the capillary tube is located in the panel where it is in heat transfer contact with a wall of the evaporator panel which is subject to the temperature of the effiuent gas or liquid. The capillary tube is embedded in a sheathing conduit in the evaporator panel which is in non-contacting heat exchange relation with the efiluent gas or liquid coming directly from the evaporator chamber, or where the evaporator includes an United States Patent accumulator as part of the evaporator chamber, the capillary tube sheathing conduit is in non-contacting heat exchange relation to eflluent gas coming from the accumulator.

The invention is specifically described in connection with the accompanying drawing wherein:

Figure 1 is a plan view of a flat evaporator plate embodying the invention;

Figure 2 is an enlarged section taken on line II-II of Figure 1;

, Figure 3 is a partly diagrammatic view illustrating the method of manufacturing the evaporator shown in Figure 1; 1

Figure 4 is a view similar to Figure 1 of a modification;

'Figure 5 illustrates the method ofmanufacture of the modification shown in Figure 4; and

Figure 6 is a section similar to Figure 2 of another modification.

Referring to the drawing, Figure 1, there is shown an evaporator plate in flat condition constructed according to the invention. The plate 1 may be made by roll bond- .ing together two sheets of aluminum 1a and 1b, as shown in section in Figure 2, having a resist therebetween to define the various passages which remain unbonded and then pressure expanding the unbonded areas to provide an evaporator passage 2 which is in the form of a serpentine passage. The evaporator is shown as a flat plate but it will be understood this plate may be bent to form a tunnel or box. The outlet connection for effluent gas from the evaporator comprises a tube 4 suitably joined, as by welding, to the evaporator plate 1 at the outlet end of the last run 5 of the evaporator passage.

Between the sheets forming the evaporator plate is provided a tubular space 6 which is disposed closely adjacent the last run 5 of the evaporator chamber. This space6 is .of such diameter as to easily receive a capillary tube 7 which passes through this space and is bent back at 8, with its end 9 welded or otherwise secured to the inlet end of run 11 of the evaporator. After the capillary tube is inserted in tubular space 6 and the end of the capillary tube is welded to the evaporator inlet end, the tubular space 6 may be reduced by crimping to firmly contact the wall of the capillary tube in heat conducting relation to the evaporator plate; or the space around tube 7 may be filled with a heat conducting filler compound. The space 6 thus serves as a sheath for the capillary tube and the wall of this sheath is in heat conducting relation to the capillary tube throughout the circumference of the capillary tube. It will be seen that in this arrangement the capillary tube 7, which supplies liquid refrigerant to the inlet end of run 11 of the evaporator, is closely adjacent and in heat exchange relation to the last or discharge run 5 of the evaporator.

This evaporator may be made by a roll bonding operation. The direct product of the roll bonding operation is shown in Figure 3 in which the plate 1 is of excessive length, and the two sheets 1a and 1b are bonded together except where a resist between the sheets provides unadhered areas comprising the tubular space 6 and the evaporator chamber 2, the latter of which includes inlet run 11 and outlet run 5. The tubular space 6 circles around at 12 to connect with the end of run 11. Thus, by applying hydraulic pressure from the two passages 5 and 6, the evaporator chamber 2, including runs 5 and 11, and tubular space 6, are expanded in one operation. Then the plate may be cut off as indicated at the dot and dash lines 13, 14 to leave space 6 open at both ends, and to open the end of run 11. The capillary tube 7 then is inserted in sheath 6, and it is bent around as indicated at 8 and Welded to the end of run 11. The wall of sheath 6 may be crimped or compressed to engage tube 7 in heat exchange relation, as shown in Fig. 2, or the space in sheath 6 around tube'7 may be filled with a heat conducting plastic or solder 10 of known suitable composition, as shown in Fig. 6.

In the modification shown in Figures 4 and 5, the evaporator chamber 2 is formed so as to have its inlet run 11 and outlet run 5 extend to opposite edges, and the evaporator chamber is so formed as to have part of the outlet run 5a closely adjacent the inlet run 11. Near the middle a section 15, outlined in dot and dash lines, is removed, after the passageway has been expanded, to provide an opening 15a. The capillary tube 7 is then inserted into the part 11a of run 11 and across space 1511 and the end of the capillary tube is welded to edge 16 of the cut away portion, so that the capillary tube connects with the inlet end of "run ll'of the evaporator, and the portion 11a may be crimped to provide intimate contact of the capillary tube with the plate 1. The cut out portion 15a allows space in which to perform the welding operation, and it will be seen the capillary tube is closely adjacent the outlet portion 5a of the evaporator chamber and in heat conducting relation thereto.

The foregoing structure and method of manufacture enables a capillary tube to be connected to the evaporator inlet end and sheathed in the wall of the evaporator plate so that the surface of the capillary tube around its periphery is in heat exchange relation to the evaporator at the outlet. This method is especially applicable to the manufacture of a roll bonded structure where it is not possible to produce a satisfactory passageway of capillary size between the sheets. However, by incorporating the sheathing tube for the capillary tube in the evaporator plate the sheathing tube may be expanded at the same time the evaporator is expanded and by the same pressure connection.

Having described my invention, I claim:

1. An evaporator structure comprising: a pair of'metal sheets bonded together in face to face relation and providing between them a pair of separation spaces, one of said spaces forming an evaporator chamber having an inlet and an outlet, and the other of said spaces forming 4 a sheathing conduit separate from said evaporator chamber; and a capillary tube extending through said conduit in heat exchange relationship with the walls of said conduit along substantially thelength of said conduit and having one end connected to said evaporator chamber inlet to supply fluid to said evaporator chamber; said conduit extending in the general direction of and closely adjacent to a portion of said evaporator chamber to provide heat exchange between the fluids flowing through said capillary tubean'd said evaporator chamber portion.

2. The evaporator structure of claim 1 wherein: said evaporator chamber portion is adjacent said evaporator chamber outlet.

7 3. The evaporator structure of claim 1 wherein: said conduit along substantially its length is compressed against said capillary tube to bring the walls of said conduit into intimate heat exchange contact with said capillary tube.

4. The evaporator structure of claim 1 wherein: the exterior diameter of said capillary tube is smaller than said conduit; and the space between said capillary tube Znld said conduit is filled with a heat conducting solid 5'. The evaporator structure of claim 1 wherein; an end of said conduit and said evaporator chamber inlet are positioned at the same edge of said structure; and said capillaryjtube includes a bent portion whichextends between said end of said conduit and said inlet.

6. The evaporator structure of claim 1 wherein: said structure has a notch separating an end of said conduit and said evaporator chamber inlet; and said capillary tube extends from said conduit end across said notch and is connected to said inlet.

References Cited in the file of this patent UNITED STATES PATENTS 2,371,215 Benson Mar. 1-3, 1943 2,446,895 Weis's Aug. 10, 1948 2,645,099 Cumming July 14, 1 953 2,694,296 Prosek et al Nov. 16, 1954 

